Oxidation of Hydrogen over Honeycomb Catalysts Under the Presence of Water Vapor

Recovery of tritium released into working areas in nuclear fusion plants is a key issue for safety. A large volume of air in the last confinement of fusion power plants should be processed by air cleanup system (ACS). In ACS, tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas high throughput of air causes higher pressure loss in catalyst and adsorbent beds. The pressure loss can be reduced by replacing the packed bed of catalysts with the honeycomb catalysts. In this study, the oxidation experiments of hydrogen in humid gases over honeycomb-type catalysts were performed, and the influence of water vapor on the rate of catalytic oxidation was investigated. The result of the experiments suggests that the rate of catalytic oxidation decreases with increasing water vapor content and its influence varies depends on the temperature. It is also indicated the rate of oxidation substantially decreases at the lower temperatures even in the case where water vapor contents is considerably lower. Therefore, it is necessary to consider the decrease in the catalytic activity by coexistent water vapor.